Critical Thinking and the ‘Real Teen’

In a recent post entitled 26% of People Polled by CNN are Nuts, Justin H (the ‘Real Teen’) claimed that

The Terrorist Surveillance Program only tapped phone lines between terrorists and another party, one of which had to be outside of the United States.

I asked a simple question in the comments to that post:

How do you know this, RT?

The answer?

No one has evidence otherwise

Let’s set aside for the moment that Justin has since deleted this exchange (he has a very low tolerance for inconvenient questions that ask him to produce facts —which is why you can see the exchange only on this mirror of the page). His answer is ludicrous on its face, since it is impossible for Justin or anyone else to know if anyone in the entire world has evidence that contradicts any given claim. One could just as easily say that there is an invisible baby elephant in Karl Rove’s garage — is this assertion proven correct merely because “no one has evidence otherwise”?

What Justin desperately needs is a crash course in critical thinking. The Wikipedia currently defines "critical thinking" as

…a mental process of analyzing or evaluating information, particularly statements or propositions that people have offered as true. It forms a process of reflecting upon the meaning of statements, examining the offered evidence and reasoning, and forming judgments about the facts.

Robert Todd Carroll has an excellent set of critical thinking mini-lessons at his site, and links to several more resources. A search on del.icio.us for the tag "criticalthinking" yields some good stuff, too. What Justin needs to understand right now is that he’s committed the classic logical fallacy of “appeal to ignorance”, also referred to as “argumentum ad ignorantiam”. As Carroll points out:

The argument to ignorance is a logical fallacy of irrelevance occurring when one claims that something is true only because it hasn’t been proved false, or that something is false only because it has not been proved true. A claim’s truth or falsity depends upon supporting or refuting evidence to the claim, not the lack of support for a contrary or contradictory claim.

(Emphasis mine.)

It simply is not possible to prove that an assertion is correct by claiming that there is no evidence that it is false. Justin would do well to learn the skills of critical thinking and logic, or his arguments will continue to be shredded by those who possess these skills.